<form [formGroup]="form" (ngSubmit)="submit()">
  <fui-select [formControl]="form.controls['username']" placeholder="select" required>
    <fui-select-option *ngFor="let option of formOptions" [value]="option.value" [label]="option.username">
      {{option.username | fuiDefault }}
    </fui-select-option>
  </fui-select>
  <button fuiBtn="primary">submit</button>
</form>